Apparatus for forming progressive power lens blanks

ABSTRACT

The present disclosure is directed to a machine and method for grinding lens blanks of progressive power in which an annular abrasive grinding ring having its internal diameter radiused is mounted for pivotal movement relative to a static frame which supports a gear driven pivotally linked lens carrier which is connected to be rocked proportional to the relative movement between the ringing ring and static frame to provide a progressive power lens measured from its bottom to top or vice versa.

United States Patent Larson et al.

[ Dec. 10, 1974 APPARATUS FOR FORMING PROGRESSIVE POWER LENS BLANKSInventors: Lawrence H. Larson, 1612 Don San Geroge CL, Orlando, Fla.32806;

Don J. Tindall, Box 1101, Orlando, Fla. 32802 Filed: Feb. 23, 1973 Appl.No.: 335,256

Related US. Application Data Continuation-impart of Ser. No. 284,098,Aug. 28, 1972, abandoned.

US. Cl. 51/33 R, 51/73 R, 51/284 Int. Cl B24b 13/04 Field of Search.....51/33 R, 73 R, 96, 99,

References Cited- 7 UNITED STATES PATENTS Briggs 5l/l24 L 3,012,37912/1961 Kuhlmann 51/33 R Primary Examiner-Al Lawrence Smith AssistantExaminer-Nicholas P. Godici Attorney, Agent, or Firm-Wilkinson,Mawhinney & Theibault [57] ABSTRACT The present disclosure is directedto a machine and method for grinding lens blanks of progressive power inwhich an annular abrasive grinding ring having its internal diameterradiused is mounted for' pivotal movement relative to a static framewhich supports a gear driven pivotally linked lens carrier which isconnected to be rocked p qportional to the relative movement between thegrinding ring and static frame to provide a progressive power lensmeasured from its bottom to top or vice versa.

6 Claims, 14 Drawing Figures PATENTEQ 35C 1 DISH SHEET 10F 5 PMEYQTEL,CUT 01974 SHEET UHF 5 ,Pmm in 1 0 m4 SHEETSUF 5 APPARATUS FOR FORMINGPROGRESSIVE POWER LENS BLANKS This application is a continuation-in-partof application Ser. No. 284.098, filed Aug. 28, 1972 and now abandoned.

An object of the present invention is to provide a machine and methodfor forming a lens with a progressive power from the top of the lens tothe bottom which must have the horizontal radii gradually decreased fromthe top of the lens to the bottom, or conversely, increased from thebottom to the top. The horizontal curves must be straight across thelens from side to side. In the vertical meridian there must be agradually changing curve similar to an involute curve. However, thechange in the vertical curve must always coincide with the change in thehorizontal curve that is the radii of the horizontal curves mustintersect with the same radius of the vertical curve. The most accurateway to measure this is with a lens measure, commonly called a lensclock.

If the clock is held against the lens with the pins horizontal and moveddownward, it will show a gradual increase in power. When the clock isheld with the pins vertical, and moved downward it will also show agradual increase in power. When the clock is held vertical and movedlaterally to the edges, it should show no deviation. If the clock isrotated with the center pin remaining on one point, it should clock thesame as a sphere (i.e., no movement of the needle).

A further object of the present invention is the provision of a machinewhich employs a rotary abrasive ring which ring has its internaldiameter radiused and which ring is pivoted at the radius for movementof the abrasive ring about a pivot on the static frame to provide arelative rocking motion between a first static frame on which the rotaryabrasive ring is mounted for rotation and the static frame. The staticframe has mounted thereon a gear driven lens carrier which is pivotallylinked to the static frame and the gears in mesh to cause the links torock the lens carrier relative to a signal to motion of one of the gearswhich is connected to be driven by the movable frame.

A still further object of the present invention is to provide a machineas described above with a template control for varying the rate of cutincident to the movement of the pivoted arms of the lens carrier and therocking of one of the gears to drive the arms to either increase ordecrease the wiping action of the lens carrier and the lens supportedthereon during grinding during passage of the lens through the annularring abrasive which is grinding the lens blank.

A still further object of the present invention is to provide a machinewhich employs a rotary abrasive ring the cross section of the peripheryof which has the contour of the lens being ground and which cooperateswith a lens carrier which is mounted to partake of both vertical andhorizontal vectors at right angles to one another which subjects thelens being ground to both a grinding and wiping action.

A lens blank constructed in accordance with the present invention mayhave prescriptions ground therein and the lens blank itself will vary inthickness from the top to the bottom so that bi-focals are not necessaryin the lens construction.

With the foregoing and other objects in view the invention will be morefully described hereinafter and more particularly pointed out in theappended claims.

In the drawings in which like parts are denoted by reference charactersthroughout the several views:

FIG. 1 is a side elevational view of a machine constructed in accordancewith the present invention.

FIG. 2 is a top plan view of the machine of FIG. 1.

FIG. 5 is a perspective view of the linkage for supporting the lenscarrier showing its driving connection with the gear drive and themovable frame.

FIG. 6 is a cross sectional view of a lens blank ground in accordancewith the method of the present invention.

FIG. 7 is a vertical section taken through the annular grinding abrasiveemployed with the movable frame of the present invention. I

FIG. 8 is a front elevational view of the annular grinding abrasive ringof FIG. 7.

FIGS. 9 and 10 are diagrammatic views of the position of the lens holderat the beginning and end ofthe grinding step.

FIG. 11 is a side elevational view of a modified form of lens grindingmachine constructed in accordance with the present'invention.

FIG. 12 is a top plan view of the lens holder and its support mechanismfor the form of machine shown in FIG. 11.

FIG. 13 is a left side elevational view of the lens holder of FIG. 12.

FIG. 14 is a section taken through the grinding abrasive wheel on theline l4-14 of FIG. 11.

Referring now to FIGS. 1 and 2, 10 designates generally the static framehaving a base 11 and ends l2, 13. Above the base 11 is a work table 14to which a movable frame 15 is pivoted at 16. The upper portion of end12 supports a motor 17 which drives a screw shaft 18 journalled inbearing 19.

The movable frame 15 has secured thereto a screw follower 20 whichmeshes with the threads of screw shaft 18 so that upon rotation of theshaft 18 the movable frame 15 will pivot about its axis of pivot 16.

Secured to the work table 14 are plates 21, 22 mounted on a support 23rigid with the work table 14.

Referring now to FIGS. 3, 4 and 5 a pair of gears 24 and 25 are mountedfor rotation on plate 21. A lens carrier 26 has a pair of arms 27, 28pivotally connected thereto. The arm 28 is longer than the arm 27 and ispivoted to plate 21 at 29, while arm 27 is pivoted to plate 22 at 30.The hub of gear 24 causes shaft 29 to rotate causing the long arm 28 toswing the lens carrier 26 as shown by the arrow in FIG. 5 from theposition shown in FIG. 3 to that of FIG. 4. Gear 24 is caused to rotateby arm 31 which is secured thereto at 32. The arm 31 is connectedthrough a template receiver 33, cam roller 34 which followsthe camsurface 35 on a cam 36 in the cam template receiver 33 under theinfluence of spring 37. The cam receiver 33 is carried by arms 38, 39which are secured to the movable frame 15 at 40.

As best seen in FIG. 2 the movable frame 15 has mounted thereon anannular ring like member of abrasive material 41, the internal diameterof which is radiused at 82, which radius defines the pivot point of themovable frame 14 at 16. The annular ring like abrasive ring 41 ismounted for rotation on a head 42, having a shaft 43 mounted in bearings44. Pulleys 45 which drive the shaft 43 and ring 41 are driven by belts46 from a motor 47 mounted on the movable frame 15.

Asshown in FIG. 6 the lens blank 48 after being ground has a variablethickness from top to bottom, or left to right. The lens blank issecured to the lens carrier 26 in accordance with conventional practicesuch as by wax or pitch.

During the grinding of a lens on the machine of the present inventionthe horizontal radius change is obtained by the abrasive ring 41 shownin FIGS. 7 and 8 whereby if the internal diameter opening of the ring 41is made with a radius of the desired highest dioptric curve and theopening is rounded to a radius thickness of the abrasive ring and thelens blank is placed against it at various angles, any curve may beobtained ranging from the opening curve to plano or flat. If a lensblank were started with its edge on the top of the internal roundedportion of the abrasive ring 41 and the angle of the abrasive werechanged gradually as the lens is moved across the rounded abrasive therewould be a gradual change of radius on the lens. With this machine theangle is gradually changed by rocking the movable frame 15 about itspivots l6. Pivot point 16 is through the radial center of the abrasivering 41 as seen in FIG. 7.

The vertical changing curve of the lens is obtained as shown in FIGS. 3,4 and in which the arms 27, 28 are pivoted at two different points atthe top and bottom of the lens holder 26. The amount of change ofcurvature and the radius of the starting curve is determined by thelength of the arms 27 and 28 and the distance between the pivot pointsof the upper ends of the arms 27, 28.

While we have referred to the abrasive ring 41 as broadly an abrasive itwill be understood that it could be a diamond compound, industrialdiamond dust or any abrasive material used commerically for polishinglens.

As shown in FIG. 1 the roller guide 34 is riding on a french curve 35which causes the gear 24 to be rotated through rocking of arm 31.

Referring now to FIGS. 9 and 10, arm 28 is shown longer than arm 27 andis separated by the difference in length at pivot points 29 and 30. FIG.9 is the starting position while FIG. is the finishing position.

In FIG. 9 the arc of long arm 28 is carried out outside point Y which isthe arc that will be cut when point Y passes the grinding point 41. InFIG. 10 the arc of short arm 27 has been carried out inside point Xwhich is the are that is cut when point X passes the grinding point 41.The angle of the straight line between points X and Y is steeper in FIG.9 than in FIG. 10, therefore in FIG. 9 the radius actually being cut atthe grinding point 41 is the radius of short arm 27 and as the arms arerotated a changing arc will be cut until the position of FIG. 10 isattained when at the grinding point 41 the radius of arm 28 is cut.

Referring now to FIGS. 11 through 14 a modified form of machine forpracticing the method and producing the lens of the present inventionwill be described. An abrasive ring 50 is mounted on a wheel 51 the axle52 of which is journalled in bearings 53 on a machine frame 54. A motor55 through pulley and V-belt drive 56 drives the abrasive ring 50.

A work holder frame 57 straddles the working surface of the abrasivering 50, as best seen in FIG. 12. A work support plate 58 is. pivoted onjournals 59 mounted in bearings 60. The plate 58 has an opening 61through which passes the lens rock shaft 62. A hearing plate 63 isretained in place by springs 64 secured to the frame 57 at one end andthe plate 63 at the other end.

As best seen in FIG. 13 the other end of the rock shaft 62 is retainedin operation position by a washer 65 connected to one end of a spring 66the other end of which is secured to plate 67 secured to two spacer bars68 having a slot 69 therebetween. The forward end of the spacer bars 68are secured to angle iron brackets which are anchored to the holderframe 57.

Lying between the plate 58 and spacer bars 68, as best seen in FIG. 12,is the lens holder 70 secured to two arms 71, 72 which are carried byand secured for rotation with the lens rock shaft 62. Secured to the arm72 is a toothed quadrant 73 in mesh with a driver worm 74 driven byshaft 75 from motor 76. Arm 71 has a roller 77 rotatably carried thereonwhich cooperates with an angle iron roller guide 78 secured between thespacer bars 68.

To grind a lens on this machine a blank is placed on the lens holder 70so that it will be engaged by the. periphery of the abrasive ring 50. Asthe lens commences to seat into the concavity of the periphery of theabrasive ring the motor 76 drives the quadrant and worm which causes thearms 71,. 72 to rock with shaft 62 downwardly in the direction of thearrow in FIG. 13. The roller 77 riding up the angle iron roller guide 78will cause the rock shaft to move in the direction of the arrows in FIG.12 which causes the plate 58 to swing in the direction of the arrowwhich springs 64 permit it to do so does spring 66 in permitting theshaft 62 which moves to the left in slot 69, shown in FIG. 13, extendingspring 66. The resultant transfer of mechanism results in wiping thelens blank across the concavity of the periphery of the rotatingabrasive wheel to grind the lens of the present invention.

What is claimed is:

1. A progressive power lens blank forming machine comprising:

a. a static frame,

b. a movable frame pivoted for movement relative to said static frame,

c. lens grinding abrasive means mounted for rotation upon said movableframe,

afirst control means connected between said static and movable frame forregulating the amount of pivotal movement between said frames,

e. lens holding means having a base, a pair of arms one end of each ofwhich is pivoted to said base, one of said arms being a short arm andthe other of said arms being a long arm, said long arm being connectedat its upper end to be gear driven from said static support and acomplemental gear in mesh therewith and connected to be rotated by saidmovable frame at a rate proportional to the rocking movement of saidmovable frame relative to said static frame to cause wiping of said lensholder across said lens grinding abrasive to grind a lens blank ofprogressive thickness f. a second control means connected between saidmovable frame and said lens holding means regulating the rate ofmovement of said lens holding means across said abrasive means as saidmovable frame is moved by said first control means relative to saidstatic frame to cut a lens blank of progressive thickness from oneextremity to the other.

2. A machine as claimed in claim 1 wherein said lens grinding abrasiveis an annular abrasive ring having its internal diameter rounded on atrue radius.

3. A machine as claimed in claim 2 wherein the movable frame is pivotedto the static frame at the plane of the center of the circle upon whichthe radius of the internal diameter of the annular abrasive ring isstruck.

control means is a motor driven screw shaft mounted on said static frameand a complementally threaded follower secured to said movable frame forcausing rocking movement of said movable frame about its pivotalconnection to said static frame.

5. A machine as claimed in claim 1 wherein said second control meanscomprises a first gear drive pivoted to said static frame and connectedto be rocked proportional to relative movement between said static andmovable frames, a second gear in mesh with said first gear and connectedto rock said lens holding means in its direction of movement toward andaway from the abrasive means.

6. A machine as defined in claim 5 further comprising a template andguide means connected between said movable frame and said first geardrive means to vary the rate and angle of wipe of said lens carrieracross said abrasive means.

1. A progressive power lens blank forming machine comprising: a. astatic frame, b. a movable frame pivoted for movement relative to saidstatic frame, c. lens grinding abrasive means mounted for rotation uponsaid movable frame, d. a first control means connected between saidstatic and movable frame for regulating the amount of pivotal movementbetween said frames, e. lens holding means having a base, a pair of armsone end of each of which is pivoted to said base, one of said arms beinga short arm and the other of said arms being a long arm, said long armbeing connected at its upper end to be gear driven from said staticsupport and a complemental gear in mesh therewith and connected to berotated by said movable frame at a rate proportional to the rockingmovement of said movable frame relative to said static frame to causewiping of said lens holder across said lens grinding abrasive to grind alens blank of progressive thickness f. a second control means connectedbetween said movable frame and said lens holding means regulating therate of movement of said lens holding means across said abrasive meansas said movable frame is moved by said first control means relative tosaid static frame to cut a lens blank of progressive thickness from oneextremity to the other.
 2. A machine as claimed in claim 1 wherein saidlens grinding abrasive is an annular abrasive ring having its internaldiameter rounded on a true radius.
 3. A machine as claimed in claim 2wherein the movable frame is pivoted to the static frame at the plane ofthe center of the circle upon which the radius of the internal diameterof the annular abrasive ring is struck.
 4. A machine as claimed in claim1 wherein said first control means is a motor driven screw shaft mountedon said static frame and a complementally threaded follower secured tosaid movable frame for causing rocking movement of said movable frameabout its pivotal connection to said static frame.
 5. A machine asclaimed in claim 1 wherein said second control means comprises a firstgear drive pivoted to said static frame and connected to be rockedproportional to relative movement between said static and movableframes, a second gear in mesh with said first gear and connected to rocksaid lens holding means in its direction of movement toward and awayfrom the abrasive means.
 6. A machine as defined in claim 5 furthercomprising a template and guide means connected between said movableframe and said first gear drive means to vary the rate and angle of wipeof said lens carrier across said Abrasive means.